Thursday, September 3, 2015

Dasht-e Kavir, The Great Salt Desert

Dasht-e Kavir, also known the Great Salt Desert, is a large desert
lying in the middle of the Iranian plateau, about 300 kilometers
east-southeast of Tehran. The desert is about 800 kilometers long and
320 kilometers wide, and composed of mud and salt marshes (kavirs). Tens
of millions of years ago, this region was occupied by a salt-rich ocean
that surround a small piece of continent in what is now central Iran.
As the ocean dried up, it left behind a layer of salt as much as 6 to 7
kilometers thick.
Over time, the layer of salt was buried under a
thick layer of mud. But salt has a fairly low density — lower than the
layer of mud and rocks underneath which the salt layer lay. So it
started pushing up through the overlying sediment and eventually, over
millions of years, the salt broke through and formed domes. The salt
domes of Dasht-e Kavir are probably some of the best examples of this
geological phenomenon.

Geologists have identified about 50 large salt domes in this region.
Some of the domes have been eroded away by wind and rain exposing its
cross-section.
Although it looks like a hard surface, the salt
crust is only a few inches thick, below which lies soft grease-like mud
the Iranians called “Charbeh” that is extremely difficult to get out of
if one were to get stuck. Because of this travelling in Dasht-e Kavir is
extremely dangerous. The soil is sterile and not suitable for
cultivation. The desert is almost uninhabited and only partly explored.
Human settling is restricted to scattered oases, where wind-blocking
housing constructions are raised to deal with the harsh weather
conditions. Some live in the hills and the surrounding mountains. Wild
sheep, camels, goats and Persian leopards also live in the mountainous
areas.

An aerial view of the eroded salt dome in the Dasht-e Kavir.

Salt flats in a low point of the Dasht-e Kavir.

Strong dry winds have dried the surface of this salt river into a web
of hair-like salt crystals. Their orientation preserves a record of the
wind as it blew across the surface.

The surface of a dry salt lake in the Dasht-e Kavir shows signs of a
hail or rain storm that pitted its surface.